Ms Dunn, of Prospect, was diagnosed with a rare form of melanoma almost a year ago.

Doctors initially thought they had contained it, her son Jim Johnstone said yesterday.

``Then eight weeks ago she had her normal scan to see how things were going and it had exploded right through her,'' Mr Johnstone said.

``She has about 50 tumours now and we expect that to grow.

``She was told eight weeks ago that she has two months left.''

Northern Tasmanian girls bike group Bikie Bitches organised the joy trike ride for Ms Dunn and her family yesterday.

Ms Dunn's daughter Dienie Binns, a member of the bike group, said her mum had no idea they were taking her on the ride until she arrived at the Black Stallion Hotel at Rocherlea about midday yesterday.

An overwhelmed Ms Dunn rode in the trike bike with her cousin Irene van der Leer.

They travelled north from the Black Stallion to the Batman Bridge and  across to Deviot and the Rosevears Tavern before returning to Launceston.

The 15 Bikie Bitches rode behind the Knees to Breeze Trike Tours bike, which was driven by Doc.

Mr Johnstone said he was glad he was able to see his mum sitting up on the trike.

``She wasn't very happy about us being on bikes when we were younger but she's seen we're safe, so it's not an issue now,'' he said.

``I'm really pleased that she's got to today as good as what she is.

``She's toughed it out and we're so proud of her.''